# Intense look at Virgo Southern Extension

Monthly Notices of the Royal Astronomical Society, Mar 2013

We collected data on radial velocities and distances of galaxies to elucidate structure and kinematics of the filament attached to the Virgo cluster from south. In the region ${\rm RA} = [12{.\!\!^{ {\mathrm {h}}}}5{--}13{.\!\!^{ {\mathrm {h}}}}5]$, Dec. = [−20°,0°] there are 171 galaxies with radial velocities VLG < 2000 km s−1, and 98 of them have distance estimates. This galaxy cloud, called as ‘Virgo Southern Extension’, is situated just on the edge of the Virgo ‘zero-velocity surface’. The mean distance to Virgo SEx, 17 ± 2 Mpc, and the average radial velocity, 1172 ± 23 km s−1, are very close to the Virgo cluster ones. In supergalactic coordinates the Virgo SEx dimensions are 15 × 7 × 2 Mpc, where the major axis is directed along the line of sight, the second major axis is directed towards the Virgo core and the minor one is perpendicular to the supergalactic plane. This flattened cloud consists of a dozen virialized groups with the total K-band luminosity of 1.7 × 1012 L⊙ and the total virial mass of 6.3 × 1013 M⊙, having a typical dark matter-to-stellar matter ratio of 37. The Hubble diagram for Virgo SEx galaxies exhibits a tendency of a Z-shaped wave with a velocity amplitude of ∼250 km s−1 that may be caused by a mass overdensity of ∼6 × 1013 M⊙, and in order of magnitude agrees with the sum of virial masses of the groups.

This is a preview of a remote PDF: http://mnras.oxfordjournals.org/content/429/3/2677.full.pdf

I. D. Karachentsev, O. G. Nasonova. Intense look at Virgo Southern Extension, Monthly Notices of the Royal Astronomical Society, 2013, 2677-2686, DOI: 10.1093/mnras/sts557